1. Field of the Present Invention
The present invention relates to a probe assembly of a prober device used for circuit inspection of plural semiconductor chips formed on a wafer in a production process of an electronic device such as LSI. More particularly, the present invention relates to a probe assembly of a prober device used for probing test that collectively measures electrical continuity of semiconductor chips by vertical probes brought into contact with circuit terminals (pads) arranged on the semiconductor chips in a wafer state.
2. Description of Prior Art
Along with the development of semiconductor technology, the integration degree of electronic devices is increasing. An area occupied by the circuit wiring is increasing in each semiconductor chip formed on a wafer and the number of circuit terminals (pads) on each semiconductor chip is also increasing. Under such circumstances, miniaturization of pad arrangement is pursued by reducing the pad area and narrowing the pad pitch, and the like. At the same time, a chip size package (CSP) is increasingly used where semiconductor chips are mounted as bear chips on a circuit board or other substrate, without being placed in a package. For this reason it is inevitably necessary to check characteristics and determine quality in the wafer state before dividing into semiconductor chips.
Particularly an issue arising out of the miniaturization of pad arrangement (narrowing of pitch) is that the probe structure is made suitable for the miniaturization of pad arrangement to obtain electrical continuity by bringing into contact with the pads of the semiconductor chips in the electrical characteristics test and circuit inspection of electronic devices. In order to address the increasingly miniaturized pad arrangement, various types of measurement methods are used.
For example, there is a method in which plural needle probes each having an elastically deformed portion that elastically deforms under an external force are arranged in area array to form a probe assembly, and then the probe assembly is interposed between pads of semiconductor chips to be inspected and an inspection apparatus. A printed wiring board called a probe card is used as means for electrically connecting the probe assembly and the inspection circuit of the semiconductor chips.
Generally in the case where a needle probe with a cantilever structure is used in a probe card, an end portion of the probe to contact a pad of semiconductor chip has a narrowed pitch. On the other hand, a root portion thereof connecting the probe card can have a rough pitch because the probe is arranged extending radially from the end portion. With such a configuration, it has been possible to fix the probe to a circuit terminal of the probe card by a connection method such as soldering. However, this cantilever structure has had the following problems. The pad is damaged as the end is displaced in horizontal direction when contacting the pad, and the measurement yield decreases as the end deviates from the pad. In addition, only one chip can be measured at a time, and it is difficult to control the contact pressure to be constant due to variation of the fitting accuracy of each probe.
In a vertical probe replacing the cantilever structure, more specifically, in a probe vertically fixed to a circuit terminal of a probe card, it is necessary to configure that the pad pitch on the semiconductor chip and the circuit terminal pitch on the probe card have the same pitch interval. However, there is technical limitation to miniaturize the circuit pattern on the probe card which is a printed wiring board. Thus it is difficult to meet the requirement of matching the pad pitch in relation to the area occupied by the circuit terminals and to the wiring width. The pitch interval available for soldering is also limited, so that it has not been possible to vertically fix the vertical probes to the probe card in line with the pad pitch of the semiconductor chip as the miniaturization has progressed.
As described above, on the probe card, a large proportion of planar area is occupied by the circuit wiring width in addition to the circuit terminal area, preventing the pitch of the circuit terminals from being narrowed. For this reason, there is also employed a method of ensuring the number of vertical probes in such a way that a multilayer printed wiring board is used as the probe card on which circuit terminals are arranged in a grid fashion or in two zigzag rows and that wiring is electrically connected between layers via through holes. However, the through holes occupy a large space, so that the presence of the through holes is a factor that prevents the pitch from being narrowed in the circuit terminal arrangement. Consequently, in vertically fixing a probe to a circuit terminal of a probe card, advanced techniques and a large number of working man-hours are required for soldering operation, in addition to the difficulty in narrowing the pitch of the circuit terminal, and thus making the cost expensive. In order to solve such problems, the present inventors have proposed a vertical probe assembly (see JP-A No. 274010/2004) and also have already proposed a prober device using the same (see JP-A No. 300545/2005)
The vertical probe assembly proposed by the inventors as the prior art, as shown in FIG. 22 of JP-A No. 274010/2004 and in FIG. 4 of JP-A No. 300545/2005, is formed by attaching a copper thin plate to a surface of a ribbon-like (strip-like) resin film, forming a vertical copper probe having a curved portion on the resin film surface by etching the copper thin plate, and laminating plural sheets of the resin film to which the probe is fixed.
As the vertical probe assembly has a structure of laminating resin films, plural probes can be arranged in a very small area. The resin film has an opening thinly extending in longitudinal direction. The probe has a vertical portion provided separating by a predetermined distance in vertical relation with a terminal at an end thereof, in which an elastically deformed portion is formed in such a way that a middle of the vertical portion is curved along the periphery of the opening in intersecting direction to the vertical portion. In this way it is designed to absorb distortion due to pressure generated when the probe end contacts the pad, by the opening of the resin film and the elastically deformed portion of the probe.
As described above, in order to disperse the pressure applied to the probe and the resin film during measurement operation, the inventors propose various forms by modifying and adjusting the size and shape of the opening of the resin film as well as the curved shape of the probe. However, although the probe assembly adapted to the narrowing of pitch can be provided with complicated process of forming resin films and probes, this would increase the production cost. The present invention provides a vertical probe assembly by use of a simple structure similar to the cantilever structure for the shape of the probe to facilitate the process of forming the opening of the resin film and the like, with less man-hour for working.
Further, it makes possible to realize a contact assembly of a grid arrangement of a small arrangement pitch by providing contacts each having an elastically deformed portion whose shape can be selected from many different types to freely determine the relative position relationship between an input portion and an output portion, and by arranging the contacts at a predetermined angle to the x axis.
In a probe assembly for performing circuit inspection of semiconductor chips, a resin film with copper foil attached thereto is used to form a conductive portion including a vertical probe on the resin film by applying etching process to the copper foil, and plural sheets of the resin film with the vertical probe are laminated, and then end portions of the vertical probes are brought into contact with electrode pads of the semiconductor chips at a time. The conductive portion including the vertical probe forms a parallelogram link having parallel springs.
As described above, the prober device using the film-laminated type vertical probe assembly that the inverters have already proposed is a device capable of measuring for semiconductor chips of a narrowed pad pitch, for example, of 45 μm or less (e.g., 20 μm pitch). In addition, mass production can be achieved at low cost as the probe can be automatically assembled without the use of fixing means such as soldering or resin. Another important advantage is that the contact pressure can be controlled uniformly for all probes that can vertically contact the chip pads at a time.
Taking advantage of theses advantages, the present invention provides a vertical probe assembly that uses a simple structure substantially similar to the cantilever structure as the shape of the probe formed in the resin film to facilitate the process of forming the opening of the resin film and the like, with less man-hour for working.
According to the present invention, a probe assembly is provided to perform circuit inspection of semiconductor chips, in which a resin film with copper foil attached thereto is used to form a conductive portion including a vertical probe on the resin film by applying etching process to the copper foil, and plural sheets of the resin film with the vertical probe are laminated, and then end portions of the vertical probes are brought into contact with electrode pads of the semiconductor chips at a time. The conductive portion including the vertical probe forms a parallelogram link having parallel springs. In the present invention, plural probes are arranged in one resin film and plural sheets of the resin film are laminated.
Further, according to the present invention, a parallelogram link mechanism having the parallel spring structure is a cantilever structure that has the vertical probe on one end side and extends in horizontal direction from the other end side as a fixed support portion. As a variation of the present invention, the parallel springs are a link mechanism that is curved and deformed in bending direction. Incidentally, as aspect of the present invention, an opening may be or may not be provided in a resin film portion corresponding to an inner space of the parallel springs.
Further, according to the present invention, there is provided a terminal portion connected to the vertical probe through the link mechanism and the conductive portion while contacting a connection pad of a circuit board of an inspection apparatus. The terminal portions are formed in the resin films so as to be arranged at positions displaced by the same pitch when the resin films with probe are laminated. Further, a curved portion is provided in the conductive portion in the vicinity of the terminal portion. As aspect of the present invention, a cut portion is provided in the vicinity between the link mechanism and the terminal portion to form the cantilever structure. As another aspect of the present invention, a dummy portion is formed by leaving a predetermined portion in addition to the conductive portion without removing the copper foil when it is etched, and by electrically separating from the conductive portion. The dummy portion serves as a reinforcing member of the resin film. Further, as still another aspect of the present invention, an insulation adhesive is filled in the resin film surface between the conductive portion and the dummy portion.
With the above described different features, the present invention has various advantages that will be described below.
In the probe assembly according to the present invention, the parallel spring structure is used as the structure of the vertical probe in the resin film with probe. Thus it is possible to reduce the move distance (displacement) of the end of the cantilever needle in the horizontal direction, compared to the move distance in the vertical direction that has been a problem in the past. This means that the probe of the cantilever structure can be used even if the pad area of semiconductor chip is miniaturized. Up to now, it has been necessary to make the vertical probe thinner as the pitch narrows down, which has limited the elastic strength of the curved portion. However, the vertical probe according to the present invention can achieve sufficient elastic strength by the cantilever structure using the parallel springs without having the curved portion. In addition, there is no need to use a complex structure such as the curved portion, so that the etching process of the copper foil is facilitated and thus the production cost can be reduced.
The contact assembly according to the present invention shows the link structure in which the shape of the parallel springs constituting the cantilever is previously deformed. In this case also, the move distance of the end portion of the vertical probe can be reduced. It is designed that the move distance has a relationship proportional to a tilt angle θ, so that the move distance can be selected without change of the deformation amount of the parallel springs when the shape is previously deformed. In other words, this structure allows the amount of friction to be determined according to the user specifications.
In the present invention, preferably the surface of the vertical probe and the surface of a positioning dummy portion are in the same plane. Further preferably a large force is not applied to the positioning dummy portion even when probing operation is performed in the z direction of the vertical probe. This is because each probe is needed to operate independently. A coupling dummy portion is formed on the tape to reduce bending in the y direction.
A first object of the present invention is to provide a vertical probe assembly formed by forming a probe of cantilever structure in a resin film to facilitate the process of forming an opening of the resin film and the like, with less man-hour for working.
A second object of the present invention is to provide a vertical probe assembly having advantages that mass production can be achieved at low cost, and that the contact pressure can be controlled uniformly for all probes that can vertically contact the chip pads at a time.
A third object of the present invention is to provide a vertical probe assembly having a dummy portion formed by leaving a predetermined portion in addition to the conductive portion without removing the copper foil when it is etched, and by electrically separating from the conductive portion in order to reinforce the resin film.
A fourth object of the present invention is to provide a vertical probe assembly in which the insulation properties between the conductive portion and the dummy portion are improved.
The foregoing objects and advantages of the present invention will be further apparent from the following description with reference to the accompanying drawings.